Ovens, and food products prepared in ovens, have been known for thousands of years. Baking food products including bread has also existed for thousands of years. Many different kinds of ovens for cooking and baking exist. Domestic ovens include conventional and convection ovens, and smaller appliances such as toaster ovens, and the like. Ovens for commercial use include those used in restaurants and those used in widespread commercial food production. Ovens for restaurants include revolving ovens, rack ovens, convection ovens, multiple deck ovens, pizza ovens, steam tube ovens, and the like. Ovens for commercial food production include direct fired tunnel ovens, steel band ovens, steel plate ovens, pita ovens, direct fired tray ovens, indirect fired tunnel ovens, and impingement ovens, and the like. All of these ovens are well known in the art, and have many advantages for their particular consumer or commercial applications. Ovens are heated directly or indirectly. Heat sources can be gas, oil, electric or other combustible materials. The heat in an oven may be generated electrically, or by using combustible fluids. The walls of commercial cooking ovens are typically metal but may be coated/layered with reflective or refractive materials, including nonstick layers and porcelain.
In all cases, satisfactory baker's ovens are difficult to produce. ‘Hot spots’ and ‘cold spots’ are created throughout the internal cooking region of most ovens, whether consumer or commercial, resulting in uneven application of heat to the baked products and reduced production. Numerous efforts have been made to eliminate this problem in commercial applications by providing rotary supports, belts, and rollers which continually move cooking products relative to the heating elements. Furthermore, efforts have been made to eliminate the problem of uneven heating, coupled with the preheating troubles and oven cleaning, in consumer ovens by varying the materials used in the walls of the ovens, and by the use of targeted temperature monitoring with controllers designed to actively adjust the thermal properties within the oven. Similar active controllers may be used in commercial applications as well. Nevertheless, the problems of uneven heat within the cooking region of traditional ovens, both commercial and consumer, remain. Inevitably some of the baked products produced in most ovens are unevenly cooked, and in commercial applications, this can result in unevenly cooked products and/or product loss from under or over cooking.
Ovens providing consistent heat throughout the internal cooking region or zones are desirable. It is desirable to provide a uniformly heated cooking region to minimize the amount of prepared food product that must be discarded. Numerous efforts have been used in the past to attempt to address this issue.
The effect of the emissivity of surfaces within ovens have been known to effect the cooking process. U.S. Patent Application No. 2010/006,559 teaches a consumer oven having an element with different coatings on the element having varying emissivity characteristics, optionally including a ceramic coating, designed to facilitate baking on one side, and broiling on the other.
The use of cooking pans, especially involving microwave cooking containers, having desirable emissivity characteristics are known in the prior art. Typically such inventions have involved simple dark paint, surface carbonizing, porcelain, or ceramic surfaces. As an example, U.S. Pat. No. 3,078,006 issued on Feb. 19, 1963 discloses a silicone resin coated metallic bake form having nonstick properties and improved radiant heat absorption characteristics in which small amounts of carbon are incorporated into the silicone resin coating. In spite of business' efforts, a sheet of cookies baked in present ovens regardless of the pan used usually result in some cookies being more cooked then others depending on their position within the cooking region.
Efforts to control the thermal environment within an oven during baking, and pans having desired thermal characteristics, are known. It is also known to provide ovens that operate, in part, by having cooking zones. The walls of some ovens have been coated in ceramic, porcelain, aluminum, dark paint, and the like in an effort to produce a desirable temperature within the cooking region or to facilitate cleaning of the sides of the oven. Other ovens simply have exposed metal surfaces.
Similarly, cooking pans have been modified to produce desirable thermal characteristics and to facilitate cleaning of the cooking surface of the pan. Simple metal racks, metal rollers, and metal conveyor belts are typically used in commercial ovens equipped with either racks, rollers, belts, or the like.
U.S. Pat. No. 6,818,869 issued on Nov. 16, 2004 teaches a multiple panel, or deck, oven having individual controls for combine conductive and radiant heating panels, and providing the option of having 1-5 different cooking zones between various panels.
U.S. Pat. No. 6,229,117 issued on May 8, 2001 teaches a bread refreshing oven having an interior lining of the oven is rebounded fused silica foam, and a tray made of fused silica in the form of a non-porous ceramic is used with the oven.
U.S. Pat. No. 4,164,643, issued on Aug. 14, 1979, teaches an energy-efficient bi-radiant oven system in which a black coated aluminum pan is disclosed with an emissivity of E=0.79; however, the oven used in this system has an oven lining with a highly reflective metal and an emissivity value on the order of E=0.05.
Energy efficient ovens with even heat distribution remain desirable. Food loss due to uneven and unpredictable oven performance remains a problem. It is desirable to have an oven which will heat evenly within a cooking zone to reliably and consistently produce the same cooked food products for mass distribution.